Poly(aryl ether sulfones) (PAES) and poly(aryl ether ketones) (PAEK) have been known for many years. PAES are tough linear polymers that possess a number of outstanding features such as excellent high temperature resistance, good electrical properties, and very good hydrolytic stability. Among the commercially available poly(aryl ether sulfones), one can notably mention Udel® polysulfone (PSU) which is a rigid, high-strength, semi-tough, transparent plastic that offers high heat resistance and hydrolytic stability, Veradel® polyethersulfone (PESU) which combines good chemical resistance with a high heat deflection temperature and inherent flame retardancy and Radel® polyphenylsulfone (PPSU) which delivers the highest performance among sulfone polymers, offering better impact resistance and chemical resistance than polysulfone (PSU). On the other hand, the highest performing semi-crystalline thermoplastics available today is KetaSpire® PEEK (polyetheretherketone) which possesses exceptional properties such as extraordinary chemical resistance, excellent strength, and superior fatigue resistance.
Many PAES and PAEK manufacturing processes have been investigated in the past. The most advantageous ones involve the use of organic solvents and inorganic bases such as sodium or potassium carbonate. Unfortunately, these processes come with several drawbacks including the recycling of organic solvents, the difficult recovery of the polymers including purification/extraction steps where insoluble salts have to be separated from the polymers and the high cost related to the processing of the salts.
Today, more than 10 million tons of organic solvents are used worldwide each year as manufacturing process aids, cleaning agents, and dispersants. The growing development of green chemistry is prompting environmentally responsible manufacturing industries to work towards the substantial diminution of the production, use, and subsequent release into the environment of contaminated water, organic solvents, and other pollutants.
Therefore, there is an interest in finding an environmentally friendly and economical process for the manufacture of poly(aryl ether sulfones) and poly(aryl ether ketones) which avoids the use of solvents and allows the easy recovery of the polymers manufactured.